At least 7 years ago I was shown an Anime that revolved around the premise that due to medical advances and low birth rate there were a lot of old people and as such there was a huge demand for old-person care nurses. One of the main characters was such a nurse, but there was also another guy as a main character.
Anyway, a company develops some high tech nursing beds that take care of bodily function needs and provides mobility but the prototype bed (and it's AI) begins interfacing with various electronics in the room and eventually becomes mobile and begins consuming other machines and devices and this bed (along with the old guy still inside) begins terrorizing downtown. Eventually the military is brought in and the bed is stopped somehow.
I'm surprised that I couldn't find it myself, but maybe I'm just unlucky. Any ideas? It's either a movie or a OVA I'd think.